Realization of 3‐degree‐of‐freedom control using fine‐grain parallel processing

Abstract

The article reports a sprout of 3‐degree‐of‐freedom (DOF) control. The limitation of feedback control, including 2‐DOF control, has been raised for a long time; however, a suitable control theory for overcoming those limitations has still not been formulated. An underlying reason is that the disturbance‐suppression performance and noise sensitivity cannot be decoupled. Several researches have tried to tackle this problem using a hardware approach, as a noise level depends on a hardware configuration. It should be noted that the hardware design expands spatiotemporal resolution of a system. This approach helps in reducing noise, namely, it works as the 3rd‐DOF for a control system. Therefore, an improvement in the hardware design could be a new angle for solving a mixed‐sensitivity problem. This article quantitatively presents the relation between noise‐reduction performance and the spatiotemporal resolution, and provides a foothold for the 3‐DOF control.